Wellbore exclusion fluid method and apparatus for downhole logging

Abstract

In some embodiments, a downhole logging tool configured for placement in a wellbore comprises a first magnet configured to activate a first volume of ferromagnetic fluid disposed between the downhole logging tool and the wellbore to achieve a first seal between a primary analysis region of the downhole logging tool and a wellbore fluid.

What is claimed is: 
     
       1. A downhole logging tool configured for placement in a wellbore, the downhole logging tool comprising:
 at least a first magnet configured to activate a first volume of ferromagnetic fluid disposed between the downhole logging tool and the wellbore to achieve a first seal between a primary analysis region of the wellbore and a wellbore fluid, and wherein the first volume of ferromagnetic fluid forms at least a first boundary of the primary analysis region; and 
 a first device positioned on the downhole logging tool and within the primary analysis region of the wellbore, wherein the primary analysis region includes a logging fluid different from the ferromagnetic fluid. 
 
     
     
       2. The downhole logging tool of  claim 1  further including:
 one or more shaping devices configured to be submerged in the ferromagnetic fluid and to provide structure to the ferromagnetic fluid. 
 
     
     
       3. The downhole logging tool of  claim 2 , wherein the one or more shaping devices include brushes configured to clear debris from the wellbore or a casing in the wellbore. 
     
     
       4. The downhole logging tool of  claim 1  further comprising:
 a second magnet configured to activate a second volume of ferromagnetic fluid disposed between the downhole logging tool and the wellbore to achieve a second seal between the primary analysis region of the wellbore and the wellbore fluid. 
 
     
     
       5. The downhole logging tool of  claim 4 , wherein the first seal is above the primary analysis region and the second seal is below the primary analysis region, wherein the first and second seals isolate the primary analysis region from the wellbore fluid. 
     
     
       6. The downhole logging tool of  claim 1  wherein the first seal is configured to remain operable during movement of the downhole logging tool. 
     
     
       7. The downhole logging tool of  claim 1 , wherein the first device comprises a sealing pad, wherein the sealing pad includes a third magnet configured to activate a third volume of ferromagnetic fluid to achieve a third seal between the sealing pad and the wellbore. 
     
     
       8. The downhole logging tool of  claim 7 , wherein the third seal between the sealing pad and the wellbore is configured to be operable during movement of the sealing pad. 
     
     
       9. The downhole logging tool of  claim 1 , wherein the ferromagnetic fluid has an oil base, aqueous base, or a fluorocarbon base. 
     
     
       10. The downhole logging tool of  claim 1 , wherein one or more sensors are configured to detect a thickness of the ferromagnetic fluid, and wherein the thickness of the ferromagnetic fluid is used to determine a position of the downhole logging tool, an angle of the downhole logging tool, or a wellbore volume at a given location. 
     
     
       11. A method comprising:
 conveying a downhole logging tool into a wellbore, wherein the downhole logging tool is configured to obtain measurements from a primary analysis region of the wellbore including a logging fluid; and 
 activating, via a first magnet, a first volume of ferromagnetic fluid disposed between the downhole logging tool and the wellbore to achieve a first seal between the primary analysis region of the wellbore and a wellbore fluid, wherein the first volume of ferromagnetic fluid forms at least a first boundary of the primary analysis region, and wherein the logging fluid is different from the ferromagnetic fluid. 
 
     
     
       12. The method of  claim 11  further comprising:
 moving the downhole logging tool while the first volume of ferromagnetic fluid is activated, wherein the first seal between the primary analysis region of the wellbore and the wellbore fluid is maintained during the movement of the downhole logging tool. 
 
     
     
       13. The method of  claim 11  further comprising:
 activating, via a second magnet, a second volume of ferromagnetic fluid to achieve a second seal between a sealing pad of the downhole logging tool and the wellbore. 
 
     
     
       14. The method of  claim 13  further comprising:
 moving the sealing pad while the second volume of ferromagnetic fluid is activated, wherein the second seal between the sealing pad and the wellbore is maintained during the movement of the sealing pad. 
 
     
     
       15. The method of  claim 11 , wherein the downhole logging tool includes one or more shaping devices configured to provide shape to the first volume of ferromagnetic fluid when the first volume of ferromagnetic fluid is activated. 
     
     
       16. A system comprising:
 a first volume of ferromagnetic fluid; and 
 a downhole logging tool configured for placement in a wellbore, wherein the downhole logging tool is configured to obtain measurements from a primary analysis region of the wellbore including a logging fluid different from the ferromagnetic fluid, and wherein the downhole logging tool includes,
 a first magnet configured to activate the first volume of ferromagnetic fluid disposed between the downhole logging tool and the wellbore to achieve a first seal between the primary analysis region of the wellbore and a wellbore fluid, wherein the first volume of ferromagnetic fluid forms at least a first boundary of the primary analysis region. 
 
 
     
     
       17. The system of  claim 16 , wherein the downhole logging tool further includes:
 one or more shaping devices configured to be submerged in the first volume of ferromagnetic fluid and to provide structure to the first volume of ferromagnetic fluid. 
 
     
     
       18. The system of  claim 17 , wherein the one or more shaping devices include brushes configured to clear debris from the wellbore or a casing in the wellbore. 
     
     
       19. The system of  claim 16 , wherein the downhole logging tool further comprises:
 a second magnet configured to activate a second volume of ferromagnetic fluid disposed between the downhole logging tool and the wellbore to achieve a second seal between the primary analysis region of the wellbore and the wellbore fluid. 
 
     
     
       20. The system of  claim 19 , wherein the first seal is above the primary analysis region and the second seal is below the primary analysis region, and wherein the first and second seals isolate the primary analysis region from the wellbore fluid.